The formation of stacked nanowires is an important step for decreasing the feature sizes of semiconductor devices.
One important issue which has to be tackled is to reduce the parasitic capacitance due to overlap between the gate and source-drain region of a transistor.
In order to minimize this parasitic capacitance, the formation of an internal spacer has to be an integral part of the nanowire integration scheme.
Forming the internal spacer adds additional requirements to the method for forming a semiconductor device comprising horizontal nanowires. There is therefore room for improvement in the methods for forming such semiconductor devices.